TWI285936B - Process for growing an epitaxial silicon layer on a semiconductor wafer - Google Patents

Abstract

A modified susceptor for use in an epitaxial deposition apparatus and process is disclosed. The modified susceptor has an inner annular ledge capable of supporting a semiconductor wafer and has a plurality of holes in the surface to allow cleaning gas utilized during an epitaxial deposition process to pass through the susceptor and contact substantially the entire back surface of the semiconductor wafer and remove a native oxide layer. Also, the plurality of holes on the susceptor allows dopant atoms out-diffused from the back surface during the epitaxial deposition process to be carried away from the front surface in an inert gas stream and into the exhaust such that autodoping of the front surface is minimized.

Description

1285936 _ Case No. 90110944_年月日日__ V. DESCRIPTION OF THE INVENTION (1) ^ Background of the Invention The present invention relates to an improved crystal holder for chemical vapor deposition. In particular, the present invention relates to an improved crystal holder having a plurality of holes for an epitaxial deposition reactor, which enables automatic doping of the front side of the semiconductor wafer and significant reduction or removal of discontinuous germanium growth on the back side of the semiconductor wafer. . In the fabrication of a monolithic crystal grown by the C ζ 〇 c h r a 1 s k i method, the polycrystalline germanium is first melted in a quartz crucible with or without doping. After the polycrystalline crucible has melted and the temperature is equilibrated, the seed crystals are immersed in the melt and then extracted to form a single crystal germanium ingot as the quartz crucible is rotated. The single crystal germanium ingot is then cut into individual semiconductor wafers which are subjected to a number of processing steps, including polishing/polishing, engraving, and buffing to produce a final semiconductor wafer having a mirror-like finish. In order to prepare the final wafer for device fabrication, the wafer may be subjected to a chemical vapor deposition method such as epitaxial deposition to grow a thin layer of germanium, typically about 0.1//m and about 200//m thick, on the front side of the wafer. The device can be made directly on the roofing layer. The conventional stray crystal deposition method is disclosed in U.S. Patent No. 5,900,7,9,5,7,6,9, 4, 2, 2, 2, 6, The stray deposition method usually involves two steps. In the first step, after the semiconductor wafer is loaded into the deposition chamber and down on the crystal holder, a cleaning gas such as hydrogen or a hydrogen/hydrochloric acid mixture is pre-baked at a front surface of the wafer at about 1150 °C. π and cleaning the front side of the wafer and removing any native oxide on the surface to allow the epitaxial layer to continuously and uniformly grow on the front side. In the second step of the epitaxial deposition method, a vapor source such as decane or trioxane is applied to the front side of the wafer at about 800 ° C or higher to deposit and grow a germanium epitaxial layer on the front side. During the two steps of the stray deposition method, the semiconductor wafer is supported by the epitaxial deposition chamber by means of a rotating crystal holder, and the crystal holder is usually rotated during the process.

O:\70\70781-960522.ptc Page 5 1285936 _ Case No. 90110944_年月曰 修正 Amendment _ V. Invention description (2) ‘ Uniform growth of Baolei crystal layer. The crystal holder is usually composed of high-purity graphite and has a layer of tantalum carbide completely covering the graphite to reduce the amount of dirt, such as self-sludge, from entering the periphery during high temperature. Conventional crystal holders for epitaxial growth methods are known in the art and are described in U.S. Patents 4,3 2 2,5 9 2, 4,4 9 6,6 0 9,5, 200, 157 and 5 , 242, 501. When a conventional crystal holder is used for epitaxial deposition, when the wafer is lowered on the crystal holder during the load process, the gas can be trapped between the crystal holder and the wafer, causing the wafer to float π while tilting. Sliding on the crystal holder. This can result in uneven epitaxial growth. In addition, during the pre-baking step, a small amount of cleaning gas such as hydrogen can be spread around the edge of the wafer between the wafer and the crystal holder, and between the wafer and the crystal holder. In the space, if the back side of the wafer is sealed with an oxide layer such as a low-temperature oxide layer, the dispersed hydrogen does not react with the oxide layer sufficiently to generate pinholes in the layer or completely remove the oxide layer. When the device manufacturer wishes to etch or polish the surface and has only a thin layer of natural oxide, the hydrogen or hydrogen/hydrochloric acid mixture will typically completely remove the native oxide layer near the outer edge of the backside, with the cleaning gas spread around the wafer and When the etch is moved inward from the outer edge of the wafer, a pinhole opening is created in the native oxide layer that exposes the surface of the wafer. These pinhole openings typically form a ring or a π-cavity around the wafer. During the crystal deposition process, a small amount of helium-containing gas may also be scattered around the edge of the wafer between the wafer and the crystallizer and into the space between the wafer and the crystal seat. If the back side of the wafer is sealed by an oxide, the ruthenium film Nucleation and growth are substantially inhibited. In the pressure where the natural oxide layer is completely etched away by the cleaning gas, a smooth continuous layer of stone is grown. However, the cleaning gas has not completely removed the natural oxide layer and the pinhole has been exposed. When 矽, 矽 containing gas can be deposited 矽

O:\70\70781-960522.ptc Page 6 1285936 Case No. 90110944 曰 Amendment V. Description of invention (3) Inside the pinhole, membrane. Therefore, the circle, which is pre-baked, results in a back shape. This lumps in the crystal of about 0.5 ohms and the like will interfere with the back of the mechanical wafer, and the pre-baking and out-diffusion of the smectite by the outer diffusion will be included in the wafer edge. Consistent use of low temperature oxygen dispersion. However, during the process, it is not advisable to attempt to eliminate the additional processing steps of the hydrogen fluoride stripping of JP11-16844 and to produce non-uniform enthalpy on the back side of the wafer during epitaxial deposition. For etching or grinding with only natural oxide layers. During the crystallizing step on the back side of the light, discontinuous enthalpy growth occurs on the pinholes in the natural oxide layer, which appears under the illumination of the blur on the back side of the blurred circle or the "void" is composed of a diameter of about It consists of a growth or bulge of 10 0 nm. This material scatters light and causes a hazy state to be considered unfavorable because of its observation and optical pyrometry system, another problem encountered during high temperature growth of the viewing layer during processing of the device is that during the high epitaxial growth step, A dopant atom such as boron or phosphorus is on the back side of the semiconductor wafer. With a conventional crystal holder, the dopant atoms from the back side are trapped between the crystal holder and the wafer itself and can be oriented toward the front side of the wafer between the aperture and the crystal holder. These dopants contaminate the deposited layer and degrade the resistance near the edge of the wafer. If the back side of the semiconductor wafer is sealed by an oxide, for example, the dopant atoms are not substantially extended from the back side, the semiconductor wafer having the etched or polished back surface is deposited by epitaxial deposition of dopant atoms from the back side. It spreads outward, which can lead to positive doping. Several methods have been proposed to eliminate back voids and autodoping. In the face of the hole, Nakamura (Japanese Unexamined Patent Application) discloses that the backside removal and/or high temperature hydrogen annealing steps are performed up to 10 days before the wafer is loaded into the stupid reaction. The addition of this method will greatly increase the complexity and cost of the deposition process.

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Deaton et al. (U.S. Patent No. 5,960,555) discloses the use of a wafer holder having an internal channel to direct a flow of scrubbing gas to the edge of the wafer along the edge of the wafer to prevent the front side of the reactive source gas from spreading to the wafer. The method of the back. This method requires substantial modification of the existing epitaxial deposition chamber and utilizes an increased flow of scrubbing gas which can cause the scrubbing gas to overflow to the front side and mix with the source gas, which deteriorates the resulting stupid film. In order to reduce the automatic doping, Hoshi (Japanese Unexamined Patent Application No. JP-A No. Hei No. No. Hei No. Hei No. Hei No. Hei No. 1 1 - 8 7 2 0 0) discloses the use of vacuum suction on the edge of a crystal holder to evacuate the boron dopant on the edge of the crystal seat and prevent automatic doping. . This method affects wafer edge uniformity and thickness and requires substantial modifications to existing epitaxial deposition systems. Nakamura (Japanese Unexamined Patent Publication No. JP-A No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei No. Hei. This method also allows a substantial amount of deposition gas to be evacuated below the backside of the wafer, which can cause the aforementioned void effects and premature corrosion and safety issues with the exhaust system. Thus, to date, methods for controlling the effects of voids on the backside of the wafer and the autodoping problems associated with the outward diffusion of dopants from the backside during the epitaxial deposition process have not been satisfactory. Therefore, there is still a need in the semiconductor industry for a simple and cost-effective solution to the effects of voids in front of germanium wafers and unsuitable for automatic doping during epitaxial deposition. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved crystal holder that allows the cleaning gas to substantially contact the entire back surface of the semiconductor wafer; the improved crystal holder arrangement significantly reduces the automatic doping of the front side of the semiconductor wafer during epitaxial growth The setting of the modified crystal seat is allowed from the semiconductor wafer circle during the pre-supply step of the stray crystal deposition_111 111 I iiiiliiiiii round __1 1 round country O:\70\70781-960522.ptc page 8 1285936 Case No. 90110944 V. Inventive Note (5) The back of the circle is real; there are many silly wafers during loading. Therefore, the device is simple, and the size and the density of the configuration port are the wafers. Hold semi-conducting 5 openings / relative off and wafer gas into the method. Room, the upper back source gas is as follows. The following figure shows the length of the crystal in the body of the common system, so that the gas is delicious and clear into the gas to completely remove the natural oxide from the introduction and substantially eliminate the hole The improved crystal seat arrangement provides improved quality using the crystal holder; and the improved crystal seat arrangement reduces or eliminates the π floating π of the wafer. In other words, the present invention relates to an epitaxial layer grown on a semiconductor wafer for use in a chemical vapor deposition process. The device includes a crystal holder having a semiconductor wafer for support. The surface of the crystal holder has an opening between about 0.2 cm/cm 2 and about 4 openings/cm 2 in parallel relation to allow fluid to flow therethrough. One step is directed to a device for stray deposition, in which a silicon semiconductor wafer is used. The device comprises a crystal holder having a size and configuration for the support circle. The surface of the crystal holder has an opening having a density of between about 0.2 and about 2 openings/cm 2 which is generally parallel to the wafer to allow fluid to flow therethrough. The apparatus further includes a support for the base rotating member, the heating element, a side ring surrounding the periphery of the base, and a gas outlet. One step in the process of growing an epitaxial layer on a semiconductor wafer includes introducing a cleaning gas into the wafer containing epitaxial deposition parallel to the front and back sides and contacting the front and back surfaces of the wafer to remove the native oxide layer. After the cleaning gas, the chamber is deposited in a stone chamber to grow an epitaxial layer on the front side. Other objects and features of the invention are described. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of the modified crystal seat of the present invention taken in the plane of line 1-1 of Fig. 2;

O:\70\70781-960522.ptc Page 9 1285936 _ Case No. 90110944_年月日日_i±±_ V. Description of the invention (6) ' Fig. 2 is a plan view of the modified crystal seat of the present invention. Figure 3 is an epitaxial reaction chamber showing the cross section of the modified crystal holder of the present invention taken in the plane of line 1-1 of Figure 2. 4 is a cross-sectional view of a modified crystal seat of the present invention. Figure 5 is a cross-sectional view of a modified crystal seat of the present invention. Corresponding reference characters indicate corresponding parts of the drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In accordance with the present invention, a high quality semiconductor wafer having an epitaxial layer on the front side is found to be formed by an epitaxial deposition chamber having a plurality of open modified crystal pads. Advantageously, the improved crystal holder substantially eliminates π floating π during loading and the fluid is transported toward and away from the back side of the wafer, and allows the cleaning gas used in the pre-baking step of the epitaxial deposition method to substantially contact the semiconductor wafer. The entire back side is substantially chemically removed from the entire native oxide layer such that during growth of the epitaxial layer, when the source gas contacts the back side of the semiconductor wafer, a smooth continuous layer of germanium is grown and the effect of voids on the back side is substantially Reduce or eliminate. In addition, the improved crystal holder allows dopant atoms contained in the semiconductor wafer to diffuse outward from the back side of the wafer during the epitaxial deposition process to be carried away from the front side of the wafer in the scrubbed gas stream and into the exhaust gas to prevent substantial mass. The dopant is interspersed between the wafer and the edge of the wafer to contact the front side, resulting in improper autodoping of the front side. Referring now to the drawings, and in particular to Figure 1, there is shown a cross-sectional view of an improved crystal holder 2 of the present invention. The modified crystal holder 2 has an inner annular flange 22 that supports the semiconductor wafer 4 having the front side 6 and the back side 8. The modified crystal holder 2 has a porous surface 9 having a plurality of holes or openings 10, 11, 12, 13, 14, 16 and 18 and a wafer lift pinhole 21. The terms opening and hole are used interchangeably herein and refer to the opening of the porous surface 9.

O:\70\70781-960522.ptc Page 10 I285936 Case No. 90110944 修正 Amendment V. Invention Description (7) - Therefore channel. The porous surface 9 having an opening is directly below the semiconductor wafer 4. As used herein, the term "multiple," means two or more apertures. Holes 1 1, 1, 1, 2, 1 3, 1 4, 16 and 18 are drilled into the modified crystal holder 2 prior to application of the coating. During the pre-bake step of the deposition process, the holes 10, 1, 1, 2, 1 3, 1 4, 16 and 18 allow the cleaning gas to substantially contact the entire back surface 8 of the semiconductor wafer 4 for cleaning The gas reacts and substantially removes all of the native oxide on the back side 8 of the semiconductor wafer 4. The backside 8 portion of the semiconductor crystal 81 4 that is in contact with the annular flange 22 in the wafer holder 2 is also substantially etched by the cleaning gas. Because the gas will scatter between the wafer and the crystal holder, resulting in substantially complete removal of the natural oxide layer on the back side. The removal of the native oxide from the back side 8 is significantly reduced or eliminated on the back side of the semiconductor wafer. Any void effect, because any source gas that is interspersed between the wafer and the crystal holder and contacts the back surface 8 during the epitaxial growth process will smoothly and continuously grow on top of the crucible surface. Holes, η, 1 2 , i 3, 2, 16 and 18 also allow for the high temperature cleaning step and the epitaxial sinking step of the epitaxial deposition method The dopant atomic via which is diffused outward from the back surface 8 of the semiconductor wafer 4 is discharged into the scrubbing gas or hydrogen stream and exits the front surface 6 of the semiconductor wafer 4 into the exhaust system. Therefore, the epitaxial deposition process can be realized. There is a significant reduction in the automatic doping of the front side during the period. Referring now to Figure 2', there is shown a top view of the inner annular flange 22 and the modified crystal holder 2 having a plurality of holes: face g4. The crystal on the porous surface 24 Round lift = ^28^0 and 32 allow the improved pinhole under the modified crystal holder 2 (not shown) to rise and fall after the semiconductor m 3 t, and improve the wafer, the nightmare, the second field, 6 surrounds the periphery of the modified crystal holder 2 and is in the entire Lei SS. 2: The spectrum I guarantees the uniformity of the temperature across the semiconductor wafer, so that the formation of the μ, 曰 匕 匕 匕 yen adversely affects the deposition process. 2 6

1285936 Case No. 90110944 Λ_ 曰 Amendment V. Description of invention (8) ^ Usually has a diameter of more than 2 4 cm to about 10 cm of the modified crystal seat and consists of high-purity graphite with a tantalum carbide or glassy carbon coating. The improved crystal holder of the present invention can be sized and configured such that the annular flange within the crystal holder can be adapted to semiconductor wafers of any diameter, including, for example, 150 mm, 200 mm, and 300 mm wafers. . The modified crystal holder can be composed of a conventional material such as high-purity graphite and has a ruthenium carbide or glassy carbon layer covering the graphite to reduce the amount of contaminants released from the graphite during the high temperature epitaxial deposition process. The graphite used to form the crystal former is typically at least about 99%, more preferably at least about 99.9%, and most preferably at least about 99.9% pure graphite. Further, the graphite preferably contains less than about 20 p p m of all metals such as iron, gallium, copper and nickel, more preferably less than about 5 p p m of all metals such as iron, molybdenum, copper and nickel. The carbonized tantalum or glassy carbon covering the graphite typically has a thickness of between about 75 microns and about 150 microns, preferably about 1 25 microns. The hole in the porous surface of the modified crystal seat directly under the semiconductor wafer preferably has a diameter such that the tantalum carbide or glassy carbon coating film is applied to the crystal seat after the hole has been drilled into the crystal seat, substantially It does not block or block the holes and thus restrict fluid flow therethrough. As will be appreciated by those skilled in the art, the opening, generally referred to as a hole, can be square, slit, diamond, forming any other shape that allows fluid to flow therethrough. 5毫米之间之间之间之间。 The opening preferably has a width of between about 0. 1 mm and about 3 mm, more preferably between about 0. 1 mm and about 1 mm, preferably between about 0.5 mm and about 1 mm. If the opening is circular, the width of the opening is defined as the maximum distance between the two corners of the opening or diameter. The apertures are spaced apart on the modified crystal holder to permit contact with the cleaning gas used during the pre-feeding step of the doped deposition process and substantially etch the entire back surface of the semiconductor wafer. The spacing of the modified crystal seat holes is about 0.5 mm and about 4 cm, more preferably about 2 mm and about 2 cm.

O:\70\70781-960522.ptc Page 12 1285936 Case No. 90110944 _η 曰 Amendment 5, between the invention description (9), preferably between about 6 mm and about 1.5 cm, the capacitive contact semiconductor The entire back side of the wafer is made available from all natural oxides. The total surface area of the open area of the crystal seat on the surface of the crystal seat is between about 5% and about 4%, more preferably between about 1% and about 3%. The surface of the crystal holder preferably has between 2 holes/cm 2 and about 4 holes/cm 2 , more preferably about 0.8 1 .75 holes/cm 2 . The density used herein means mean. It is generally preferred that the aperture of the modified crystal holder be as small as possible so that the tantalum carbide or glassy carbon coating film restricts fluid flow through the aperture to the back side. If the hole in the crystal seat is drilled too large, the nanometer surface on the front side of the wafer caused by the unevenness of the back surface improves the large diameter hole in the crystal seat, and the direct irradiation of the semiconductor wafer through the back surface can be Lead to the development of hot spots or cold spots on the surface. This hot or cold point causes a temperature level that is formed on the front side and can cause growth on the front side of the semiconductor wafer. The uneven growth of the epitaxial layer significantly deteriorates the hole in the wafer can be drilled into the crystal seat at an oblique angle to directly irradiate the heating lamp and the formation of hot or cold spots leads to the possibility of positive epitaxial growth, but The gas permeable crystal holder is still allowed to allow the outward diffusion of dopant atoms to be removed from the back side. For the formation of hot or cold spots and the generation of temperature levels due to direct illumination of the through-wafer vias and the reduction or elimination of any heat or cold spots, the lamp power ratio of the lamps on the semiconductor wafer can be adjusted and adjusted. The lamp produces a balanced heat. The actual percentage of the backside etching of the cleaning gas is that the density of the crystal holder is about 0. The hole/cm 2 is approximately uniform or non-uniformly dense. The semi-conducting problem is below the semi-conducting half-inferior quality step-down surface. And in the half-lift needle, the lower diameter, the body-shaped part of the crystal will be added to the body-shaped crystal conductor to tamper with less back without touching the one-step conductor hole but not the temperature of the temperature. Heat lamp round back wafer crystallized fine surface is evenly surfaced and reduces wafer heating

O:\70\70781-960522.ptc Page 13 1285936 _ Case No. 90110944_年月曰曰 Revision _ V. INSTRUCTION DESCRIPTION (10) _ The improved crystal seat of the present invention can be used as a chemical vapor deposition method such as epitaxial deposition Part of the device of the law. Referring now to Figure 3, there is shown an epitaxial reaction chamber 34 for use during the epitaxial growth process using the improved crystal holder 36 of the present invention. The modified pedestal 36 is attached to the rotatable support members 58 and 59 and is sized and configured to support the semiconductor wafer 38 on the inner annular flange 42 during the epitaxial deposition process. The semiconductor wafer 38 is spaced apart from the holes 4 4, 4 5, 4 6, 4 7, 4 8, 4 9 and 5 1 in the porous surface 49 of the modified crystal holder 36. The lifting pinhole 6 2 allows the lifting pin (not shown) to pass through the outer hole surface 9 of the modified crystal seat 36 to the semiconductor wafer 3, so that the semiconductor wafer 38 rises before and after the epitaxial deposition process. And leave the modified crystal seat 3 6 . The house crystal deposition chamber 34 also contains a lamp array 50, 52, which is located above and below the modified crystal holder 36 for heating during the epitaxial deposition process. The gas inlets 5 4, 5 6 allow the introduction of the cleaning gas during the pre-baking step of the epitaxial deposition process, and the cleaning gas is introduced above and below the semiconductor wafer 38 to strengthen the front surface 60 of the semiconductor wafer 38 and the back surface 6 2 removal of natural oxides. During the epitaxial growth step, the gas inlet 54 is introduced with a helium-containing gas flowing over the wafer 38, and the gas inlet 56 is introduced with hydrogen or an inert gas under the wafer 38 to rinse the back of the semiconductor wafer 38. 6 2 and from the front side to the external diffusion of dopant atoms. As shown in Fig. 3, the gas injected into the stray deposition chamber flows parallel to the front and back sides of the semiconductor wafer. The flow pattern allows the injected gas to contact the front side and penetrate the crystal holder through the holes in the surface of the wafer holder to contact the back side of the wafer. Because the gas flows parallel to the semiconductor surface rather than vertically, the semiconductor wafer is significantly reduced or eliminated by the possibility of gas that is interspersed between the edge of the wafer and the edge of the annular flange and that is deformed away from the annular flange. The gas system from the gas inlet 5 4, 5 6 into the chamber 34 is removed from the chamber 34 through the exhaust port 64.

O:\70\70781-960522.ptc Page 14 1285936 Case No. 90110944 Λ_η 曰 Amendment 5, Invention Description (11). Improvement of the hole in the crystal seat will allow the cleaning gas to pass through the modified crystal seat and substantially contact during the cleaning step The entire back side of the semiconductor wafer is such that any natural oxide present on the back side is removed by the cleaning gas. The removal of this native oxide from the back side will allow a smooth continuous epitaxial layer to be grown on any portion of the back side of the semiconductor wafer, which is in contact with the source gas during growth of the epitaxial layer, thus essentially eliminating any The formation of a void on the back. In addition, the holes in the modified crystal holder will allow the inert gas or hydrogen to contact the back side of the wafer, so that the dopant atoms diffused outward from the back surface during the cleaning step and the epitaxial growth step will be carried away from the semiconductor wafer into the exhaust gas. Medium, thus substantially reducing the likelihood of automatically doping the front side of the wafer. An epitaxial reaction chamber containing the above-described improved crystal holder of the present invention can be used for the cleaning and growth steps of the epitaxial deposition method. In an epitaxial deposition process in accordance with the present invention, an epitaxial layer is grown on the front side of a semiconductor wafer. In a preferred embodiment of the invention, the germanium wafer is introduced into the epitaxial deposition chamber at ambient pressure, and the cleaning gas such as hydrogen or a mixture of hydrogen and hydrochloric acid at a temperature of about 1000 ° C and about 1 30 At 0 ° C, the flow rate is between about 1 liter / minute and about 50 liter / minute, preferably between about 10 liter / minute and about 20 liter / minute, and introduced into the chamber for at least about 10 seconds to remove the semiconductor. A natural oxide layer on the front and back of the wafer. Once the natural oxide layer is removed from the front and back sides of the semiconductor wafer, the cleaning gas is interrupted and the temperature in the reaction chamber is adjusted to between about 60 ° C and about 1 20 ° C, containing a helium source gas such as decane. Or the thickness of the epitaxial layer is about 0.1 Å and 约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约约A semiconductor crystal between 200 μm, preferably between about 1 and about 100 μm

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- Case No. 90110944 V. Description of invention (12) On the front side of the circle. At the same time, the helium-containing gas is introduced into the semi-conducting deposition chamber, and the gas such as nitrogen, argon, hydrogen, and the mixture f thereof has an upper k-speed of between about 1 liter/min and about 50 liter/min, preferably a gas original emulsion. Between the clock and about 20 liters/minute, the liters/mins introduced into the semiconductor wafer are such that the scrubbing gas can contact the back side of the semiconductor wafer and from the underside of the dopant dopant atoms toward the discharge outlet. Preferably, the external expansion eliminates any back cavity effect and reduces the automatic doping of the front side by 1 f. The preferred method is to perform the system under ambient pressure, but the deposition method is also in the present invention. Within the scope. Pre-gas phase In an alternative embodiment of the invention, the modified crystal holder can be made large to allow the semiconductor wafer to directly reside on the porous surface, thereby eliminating the flange 22, as shown in FIG. Referring now to Figure 4, there is shown a modified crucible section in which the semiconductor wafer resides directly on the porous surface. The back side 76 of the circle 70 is directly seated on the porous surface 72 of the modified wafer holder 74. The back side 76 of the wafer 70 directly contacts the porous surface 72, but flows through the gas permeable aperture 78, 80 below the modified 曰^74. , 8 2, 8 4, 8 6, 8 8 and 9 〇 penetration / surface 7 2 and substantially contact the entire back surface 7 of the wafer 70. In another alternative embodiment, the improved crystal holder of the present invention shown in Figure 4 can be further modified such that the porous surface 72 is disk-shaped or dome-shaped to permit only the outer edge of the semiconductor wafer to contact the modified crystal holder. Referring now to Figure 5, there is shown a cross section of an improved crystal holder in which the semiconductor wafer resides directly on the porous surface of the crystal holder. The back surface 71 of the semiconductor wafer 70 is directly seated on the porous surface 71 of the modified crystal holder 74. The porous surface 72 is shaped like a disk or dome such that the outer edge 9 2, 94 of the semiconductor wafer 7 is in direct contact with the porous surface 72 and the back portion 76 or the remainder of the wafer 70 is not in direct contact with the multi-surface 7 2. During use, holes 7 8,8 0,

O:\70\70781-960522.ptc Page 16 1285936 Case No. 90110944 曰Revision 5, Invention Description (13) * 8 2,8 4,8 6,8 8 and 90 allow fluid to flow through to the wafer back. It will be apparent to those skilled in the art that the improved crystal holder of the present invention can be used with a variety of deposition reactors, including barrel, pancake, and micro-batch reactors, regardless of the shape of the wafer holder used. In view of the above, it will be appreciated that several objects of the invention are attained. Since the above-described modified crystal holders can be variously modified without departing from the scope of the invention, it is intended that all of the above-described aspects be construed as illustrative and not limiting.

O:\70\70781-960522.ptc Page 17 1285936 Case No. 90110944 Λ _ 曰 Correction diagram Simple description of the main components Symbol Description 2, 36, 74 4, 38, 70 6, 60 8, 62, 76 9,24, 49,72 modified wafer semiconductor wafer front and back porous surface 10, 11,12, 13, 14, 16, 18, 44, 45, 46, 47, 48, 49, 51,78, 80, 8 2, 8 4 , 8 6, 8 8, 9 0 hole / opening 21,2 8, 3 0, 3 2, 6 2 22,42 Wafer lifting pinhole inner flange 26, 40 34 58 50 54 64 92,94 side Ring 59 52 56 insect crystal reaction chamber rotatable support member heating lamp array gas inlet exhaust rim

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Claims (1)

1285936 _ Case No. 90110944 X Year 0 Month #日修正_ Six, application patent range '1 · A method of growing an epitaxial layer on a semiconductor wafer, the semi-conductor wafer has a front side and a back side, The method comprises: introducing a cleaning gas into an epitaxial deposition chamber containing a semiconductor wafer, and flowing the cleaning gas parallel to the front and back surfaces and contacting the front surface of the semiconductor wafer and substantially the entire back surface of the semiconductor wafer from the semiconductor wafer Removing a natural oxide layer from the front side and the back side; and introducing a stone-containing source gas into the stray crystal deposition chamber to grow a stucco layer on the front side of the semiconductor wafer, and introducing the cleaning gas into the stray crystal deposition chamber The dopant atoms that are externally diffused between the back side of the semiconductor wafer are removed from the front side of the semiconductor wafer. 2. The method of claim 1, wherein the epitaxial layer is between about 0.1 micron and 200 microns thick. 3. The method of claim 1, further comprising supporting the semiconductor wafer with a wafer holder when the cleaning gas is introduced into the deposition chamber. 4. The method of claim 1, 2 or 3, further comprising supporting the semiconductor wafer with a wafer holder when the helium-containing gas and the scrubbing gas are introduced into the deposition chamber. 5. The method of claim 1, 2 or 3, further comprising supporting the semiconductor wafer with a crystal holder and allowing the cleaning gas and the scrubbing gas to pass through the plurality of holes of the crystal holder to penetrate the crystal holder to contact the wafer The back. 6. The method of claim 1, 2 or 3, wherein the cleaning gas comprises hydrogen and the cleaning gas is introduced into the deposition chamber at a temperature of about 1000 ° C and about 130 ° C. . O:\70\70781-960522.ptc Page 19 1285936 _ Case No. 90110944_年月日日 Revision _ 6. Patent application scope 7. According to the method of claim 6, wherein the cleaning gas system has a flow rate of about 1 Liters/minutes are introduced between approximately 50 liters/minute. 8. The method of claim 7, wherein the cleaning gas is introduced into the deposition chamber for at least about 10 seconds. 9. The method of claim 1, 2 or 3, further comprising supporting the semiconductor wafer with a ring-shaped inner flange. The method of claim 9, wherein the support of the semiconductor wafer comprises a plurality of holes in the crystal holder to support the semiconductor wafer in spaced relationship. O:\70\70781-960522.ptc Page 20